HeadMeds gives young people in the United Kingdom general information about medication. HeadMeds does not give you medical advice. Please talk to your Doctor or anyone else who is supporting you about your own situation because everyone is different. Please read more important details about our site.

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Return to Mirtazapine overview
  1. Use and Action
  2. Warnings and side effects
  3. Sex, drink, weight and everything else
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Taking olanzapine
It is scary, starting a drug, especially one that holds various negative associations

You can drink alcohol while taking mirtazapine, but it could make you very sleepy

  • You can continue to drink alcohol while taking mirtazapine but having the two together might make you very sleepy and unsteady on your feet.
  • So, during the first few days, it might be best to stop drinking alcohol until you see how the medicine affects you or the side-effects pass.
  • If you want to drink alcohol, remember that you might be very sleepy and make sure you can get home safely.
  • Drinking alcohol every day, or in large amounts, can make your symptoms worse and the mirtazapine will not get the best chance to act.

Do not drive a car or ride a bike just after you start taking mirtazapine

  • Taking mirtazapine may make you feel tired or dizzy, or less alert, when you start taking it.
  • This could affect you if you drive a car, ride a bike, use machines, or do anything else that needs a lot of focus. It might be best to stop doing these things for the first few days, until you know how it affects you or the side-effects pass.
  • Do not worry - most people drive as normal while taking mirtazapine.

Try not to take mirtazapine for the first time just before your exams

  • Taking mirtazapine may make you feel tired or dizzy, or less alert, when you start taking it.
  • You should talk to your doctor about any future exams if you are starting mirtazapine.
  • You might decide together to delay starting it until you have done them.
  • If they are more than a month away, however, you might find that it is better to start mirtazapine to improve your motivation to study.
  • Do not worry - most people do exams as normal while taking mirtazapine.

Mirtazapine is not a banned substance in sport

  • Mirtazapine is not a banned substance in sport.
  • You might, however, feel sleepy or less alert.
  • If you play sport that needs a lot of focus, it might be best to stop until you know how mirtazapine affects you.
  • Do not worry - most people do sports as normal while taking mirtazapine.

Your weight can be affected by mirtazapine

  • A side-effect of mirtazapine can be feeling more hungry and weight gain.
  • This happened more often in young people than in older adults.
  • Talk to your doctor about this if it worries you.

Mirtazapine may make you feel very sleepy, but may also make it hard to get to sleep

  • Mirtazapine can make you feel very sleepy.
  • Some people can get a side-effect where it makes it difficult to get to sleep.
  • Talk to your doctor about this if it happens to you, and does not get better after a few days.

Let your family and friends know you are taking mirtazapine so they can support you and help you look out for side effects

  • The side-effects of mirtazapine might put a strain on your friendships and relationships, especially in the first few days of taking it.
  • You might feel aggressive, restless or anxious.
  • These side-effects should get better after a few days.
  • You should then be getting the good effects of mirtazapine, and that should improve your relationships in itself.
  • It might actually be a great idea to choose a good friend to tell about your medicine when you start taking it. (Or - even better - to take a friend with you to the doctor before you start taking the medicine!)
  • They could look at the medicine leaflet, or at this website.
  • They could help you to understand whether the medicine changes your behaviour, or gives you side-effects (sometimes it is hard for us to see it ourselves).

Mirtazapine can have side-effects that might affect your sex life

The good effects of mirtazapine may have a good effect on your sex life as your symptoms settle and you can concentrate on your relationships. In fact, mirtazapine isn’t thought to have a significant effect on libido, arousal and orgasmic ability. However, there are some side effects that include:

  • Weight gain or a rash, which might make you feel less sexy

If your rash gets worse or weight gain is a problem for you, go back to the doctor and see what else you could try.

We do not know whether mirtazapine can affect fertility

  • There is nothing to suggest that mirtazapine affects fertility.

Is it safe to take mirtazapine in pregnancy?

Studies of over 600 mums taking mirtazapine in the first trimester show no increase in problems in the baby nor risk of malformations when usual doses have been taken.
There may be a very slight increase in the risk of miscarriage or having a baby born early.
If mirtazapine is taken after 20 weeks of pregnancy there is in theory a risk of Persistent Pulmonary Hypertension in the Newborn (PPHN) but there is not enough research to say if this happens with mirtazapine or not.
Do discuss your options with your doctor but remember babies do better with well mums.
PPHN may cause some breathing problems in your baby
Your baby could have some discontinuation symptoms such as being irritable, crying, shivering or problems sleeping. These are usually mild and go away in a few days without treatment.
Your baby’s blood sugar is likely to be checked as in rare cases it may be too low.

Mirtazapine is passed to the baby in breast milk

  • Mirtazapine is passed to the baby in breast milk in small amounts but this can help with any discontinuation symptoms.
  • Remember that it is important for you to remain well whilst you are bonding with and looking after your baby. For this reason, it may be best to take medicine for your mental health when breastfeeding.
  • You may also need to consider bottle feeding with formula milk if there are any problems with breastfeeding whilst taking medicines.
  • Talk to your doctor or midwife about your feeding options.
  • Make sure that your doctor, nurse, or health visitor checks your baby for any side effects. These can include:
  • Being extra sleepy
  • Having colic
  • Feeding problems
  • Being floppy
  • Poor weight gain

If you start or stop smoking while you are taking mirtazapine, you may have to change your dose

  • Cigarette smoke affects the amount of mirtazapine in your body.
  • If you smoke, you may need a higher dose of mirtazapine than someone who does not smoke.
  • Tell your doctor if you smoke, so that you get the right dose for you.
  • If you stop smoking, the body’s mirtazapine level rises and you might need to reduce your dose of mirtazapine slowly over one week.
  • If you (re)start smoking, you will probably need to increase it again.
  • Go to your doctor for advice if you stop or start smoking.

Reference Sources 

Search www.medicines.org.uk to find patient information leaflets and prescribing information on mirtazapine. Tablets, orodispersible tablets and liquid are listed separately. The SmPC lists all the inactive ingredients in the product so you can check against any allergies. If you are still unsure about this then speak to your pharmacist.

  • British National Formulary (BNF) and British National Formulary for children. Download the BNF/BNFC app (blue background) on to your mobile device. No longer available for public access via the web 
  • Taylor D, Barnes T, Young A. Maudsley Prescribing Guidelines in Psychiatry, 13th edition. Oxford: John Wiley & Sons, May 2018. ISBN: 978-1-119-44260-8
  • Royal Pharmaceutical Society. Medicines Ethics and Practice (42nd edition). London: RPS, 2018. Standards for pharmacists to work to. It is not a free publication
  • World Anti Doping Agency WADA Prohibited List https://www.wada-ama.org/en/resources/science-medicine/prohibited-list-documents 
  • Choiceandmedication; an independent source of information on many mental health conditions and their medicines with easy to read fact sheets www.choiceandmedication.org Personal subscriptions to download the app available for £1 per month (with proportionate discounts for longer periods) but your local mental health Trust may subscribe and provide information sheets for free.
  • Best Use of Medicines in Pregnancy (BUMPS). Information sheets on drugs in pregnancy http://www.medicinesinpregnancy.org/ 
  • Drugs and Lactation Database (LactMed). Information on drugs in breastfeeding https://toxnet.nlm.nih.gov/newtoxnet/lactmed.htm